summaryrefslogtreecommitdiff
path: root/types.c
blob: e2a1bf163e51318e215e072adc94af14bec10ca4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
/*
  Copyright (C) 2019, 2020 Leo Tenenbaum.
  This file is part of toc. toc is distributed under version 3 of the GNU General Public License, without any warranty whatsoever.
  You should have received a copy of the GNU General Public License along with toc. If not, see <https://www.gnu.org/licenses/>.
*/
static bool types_stmt(Typer *tr, Statement *s);
static bool types_block(Typer *tr, Block *b);
static bool type_resolve(Typer *tr, Type *t, Location where);

static inline void *typer_malloc(Typer *tr, size_t bytes) {
	return allocr_malloc(tr->allocr, bytes);
}

static inline void *typer_calloc(Typer *tr, size_t n, size_t sz) {
	return allocr_calloc(tr->allocr, n, sz);
}

static inline void *typer_arr_add_(Typer *tr, void **arr, size_t sz) {
	return arr_adda_(arr, sz, tr->allocr);
}

static inline bool type_is_builtin(Type *t, BuiltinType b) {
	return t->kind == TYPE_BUILTIN && t->builtin == b;
}

#define typer_arr_add(tr, a) typer_arr_add_(tr, (void **)(a), sizeof **(a))

static bool type_eq(Type *a, Type *b) {
	if (a->kind == TYPE_UNKNOWN || b->kind == TYPE_UNKNOWN)
		return true; /* allow things such as 3 + #C("5") */
	assert(a->flags & TYPE_IS_RESOLVED);
	assert(b->flags & TYPE_IS_RESOLVED);
	
	if (a->kind != b->kind) return false;
	if (b->flags & TYPE_IS_FLEXIBLE) {
		Type *tmp = a;
		a = b;
		b = tmp;
	}

	if (a->flags & TYPE_IS_FLEXIBLE) {
		if (b->flags & TYPE_IS_FLEXIBLE) return true;
		assert(a->kind == TYPE_BUILTIN);
		
		if (type_builtin_is_float(a->builtin)) {
			return type_builtin_is_float(b->builtin);
		}
		assert(a->builtin == BUILTIN_I64);
		return type_builtin_is_numerical(b->builtin);
	}
	switch (a->kind) {
	case TYPE_VOID: return true;
	case TYPE_UNKNOWN: assert(0); return false;
	case TYPE_TYPE: return true;
	case TYPE_BUILTIN:
		return a->builtin == b->builtin;
	case TYPE_STRUCT: return a->struc == b->struc;
	case TYPE_FN: {
		if (arr_len(a->fn.types) != arr_len(b->fn.types)) return false;
		Type *a_types = a->fn.types, *b_types = b->fn.types;
		Constness *a_constness = a->fn.constness, *b_constness = b->fn.constness;
		for (size_t i = 0; i < arr_len(a->fn.types); ++i) {
			Constness const_a = CONSTNESS_NO, const_b = CONSTNESS_NO;
			if (a_constness)
				const_a = a_constness[i];
			if (b_constness)
				const_b = b_constness[i];
			if ((const_a == CONSTNESS_NO && const_b == CONSTNESS_YES)
				|| (const_a == CONSTNESS_YES && const_b == CONSTNESS_NO))
				return false;
			if (!type_eq(&a_types[i], &b_types[i]))
				return false;
			
		}
		return true;
	}
	case TYPE_TUPLE: {
		if (arr_len(a->tuple) != arr_len(b->tuple)) return false;
		Type *a_types = a->tuple, *b_types = b->tuple;
		for (size_t i = 0; i < arr_len(a->tuple); ++i) {
			if (!type_eq(&a_types[i], &b_types[i]))
				return false;
		}
		return true;
	}
	case TYPE_ARR:
		if (a->arr.n != b->arr.n) return false;
		return type_eq(a->arr.of, b->arr.of);
	case TYPE_SLICE:
		return type_eq(a->slice, b->slice);
	case TYPE_PTR:
		return type_eq(a->ptr, b->ptr);
	case TYPE_EXPR:
		break;
	}
	assert(0);
	return false;
}

/* expected must equal got, or an error will be produced */
static bool type_must_eq(Location where, Type *expected, Type *got) {
	if (!type_eq(expected, got)) {
		char *str_ex = type_to_str(expected);
		char *str_got = type_to_str(got);
		err_print(where, "Type mismatch: expected %s, but got %s.", str_ex, str_got);
		return false;
	}
	return true;
}

/* prints an error and returns false if the given expression is not an l-value */
static bool expr_must_lval(Expression *e) {
	/* NOTE: make sure you update eval when you change this */
	switch (e->kind) {
	case EXPR_IDENT: {
		IdentDecl *id_decl = ident_decl(e->ident);
		assert(id_decl);
		if (id_decl->kind == IDECL_DECL) {
			Declaration *d = id_decl->decl;
			if (d->flags & DECL_IS_CONST) {
				char *istr = ident_to_str(e->ident);
				err_print(e->where, "Use of constant %s as a non-constant expression.", istr);
				info_print(d->where, "%s was declared here.", istr);
				return false;
			}

		}
		return true;
	}
	case EXPR_UNARY_OP:
		if (e->unary.op == UNARY_DEREF) return true;
		if (e->unary.op == UNARY_LEN) {
			Type *of_type = &e->unary.of->type;
			if (of_type->kind != TYPE_PTR && !expr_must_lval(e->unary.of)) { /* can't set length of a non-lvalue slice */
				return false;
			}
			
			return of_type->kind == TYPE_SLICE
				|| (of_type->kind == TYPE_PTR
					&& of_type->kind == TYPE_SLICE);
		}
		err_print(e->where, "Cannot use operator %s as l-value.", unary_op_to_str(e->unary.op));
		return false;
	case EXPR_BINARY_OP:
		switch (e->binary.op) {
		case BINARY_AT_INDEX:
			if (!expr_must_lval(e->binary.lhs))
				return false;
			return true;
		case BINARY_DOT: return true;
		default: break;
		}
		err_print(e->where, "Cannot use operator %s as l-value.", binary_op_to_str(e->binary.op));
	    return false;
	case EXPR_TUPLE:
		/* x, y is an lval, but 3, "hello" is not. */
		arr_foreach(e->tuple, Expression, x) {
			if (!expr_must_lval(x)) 
				return false;
		}
		return true;
	case EXPR_CAST:
	case EXPR_NEW:
	case EXPR_FN:
	case EXPR_LITERAL_FLOAT:
	case EXPR_LITERAL_CHAR:
	case EXPR_LITERAL_STR:
	case EXPR_LITERAL_INT:
	case EXPR_LITERAL_BOOL:
	case EXPR_IF:
	case EXPR_WHILE:
	case EXPR_EACH:
	case EXPR_CALL:
	case EXPR_C:
	case EXPR_DALIGNOF:
	case EXPR_DSIZEOF:
	case EXPR_BLOCK:
	case EXPR_SLICE:
	case EXPR_TYPE:
	case EXPR_VAL: {
		err_print(e->where, "Cannot use %s as l-value.", expr_kind_to_str(e->kind));
		return false;
	}
	}
	assert(0);
	return false;
}

enum {
	  /* is f an instance? (changes behaviour a bit) */
	  TYPE_OF_FN_IS_INSTANCE = 0x01
};

static bool type_of_fn(Typer *tr, FnExpr *f, Type *t, U16 flags) {
	t->kind = TYPE_FN;
	t->fn.types = NULL;
	t->fn.constness = NULL; /* OPTIM: constness doesn't need to be a dynamic array */
	bool success = true;
	bool entered_fn = false;
	size_t param_idx;
	FnExpr *prev_fn = tr->fn;
	FnExpr fn_copy = {0};
	
	Block *prev_block = tr->block;
	/* 
	   fakely enter the body of the function, so that
	   fn (x : int) y := x {} works
	*/
	tr->block = &f->body;
	*(Block **)arr_adda(&tr->blocks, tr->allocr) = tr->block;
		
	/* f has compile time params, but it's not an instance! */
	bool generic = !(flags & TYPE_OF_FN_IS_INSTANCE) && fn_has_any_const_params(f);
	if (generic) {
		Copier cop = copier_create(tr->allocr, tr->block);
		copy_fn_expr(&cop, &fn_copy, f, false);
		f = &fn_copy;
	}
	size_t idx = 0;
	bool has_constant_params = false;
	Type *ret_type = typer_arr_add(tr, &t->fn.types);
	if (!fn_enter(f, SCOPE_CHECK_REDECL))
		return false;
	tr->fn = f;
	size_t nparams = arr_len(f->params);
	entered_fn = true;
	for (param_idx = 0; param_idx < nparams; ++param_idx) {
		Declaration *param = &f->params[param_idx];
		if (!generic) {
			if (!types_decl(tr, param)) {
				success = false;
				goto ret;
			}
			
			if (param->type.kind == TYPE_TUPLE) {
				err_print(param->where, "Functions can't have tuple parameters.");
				success = false;
				goto ret;
			}
			
			if (param->flags & DECL_HAS_EXPR) {
				if (param->expr.kind != EXPR_VAL) {
					Value val;
					if (!eval_expr(tr->evalr, &param->expr, &val)) {
						info_print(param->where, "Was trying to evaluate default arguments (which must be constants!)");
						success = false;
						goto ret;
					}
					param->expr.kind = EXPR_VAL;
					param->expr.val = val;
					if (param->expr.type.flags & TYPE_IS_FLEXIBLE) {
						/* cast to the annotated type, if one exists */
						if (param->flags & DECL_ANNOTATES_TYPE) {
							val_cast(&param->expr.val, &param->expr.type, &param->expr.val, &param->type);
							param->expr.type = param->type;
						}
					}
				}
			} 
		}
		U32 is_at_all_const = param->flags & (DECL_IS_CONST | DECL_SEMI_CONST);
		if (is_at_all_const) {
			if (!t->fn.constness) {
				has_constant_params = true;
				for (size_t i = 0; i < idx; ++i) {
					*(Constness *)typer_arr_add(tr, &t->fn.constness) = CONSTNESS_NO;
				}
			}
		}
		for (size_t i = 0; i < arr_len(param->idents); ++i) {
			Type *param_type = typer_arr_add(tr, &t->fn.types);
			if (!generic) {
				*param_type = param->type;
			} else {
				param_type->flags = 0;
				param_type->kind = TYPE_UNKNOWN;
			}
			if (has_constant_params) {
				Constness constn;
				if (param->flags & DECL_IS_CONST) {
					constn = CONSTNESS_YES;
				} else if (param->flags & DECL_SEMI_CONST) {
					constn = CONSTNESS_SEMI;
				} else {
					constn = CONSTNESS_NO;
				}
				*(Constness *)typer_arr_add(tr, &t->fn.constness) = constn;
			}
			++idx;
		}
	}
	
	if (f->ret_decls && !generic && f->ret_type.kind == TYPE_VOID /* haven't found return type yet */) {
		/* find return type */

		arr_foreach(f->ret_decls, Declaration, d) {
			if (!types_decl(tr, d)) {
			    success = false;
				goto ret;
			}
		}
	
		if (arr_len(f->ret_decls) == 1 && arr_len(f->ret_decls[0].idents) == 1) {
			f->ret_type = f->ret_decls[0].type;
		} else {
			f->ret_type.kind = TYPE_TUPLE;
			f->ret_type.flags = TYPE_IS_RESOLVED;
			f->ret_type.was_expr = NULL;
			f->ret_type.tuple = NULL;
			f->ret_type.where = f->ret_decls[0].where;
			arr_foreach(f->ret_decls, Declaration, d) {
				arr_foreach(d->idents, Identifier, i) {
					*(Type *)arr_add(&f->ret_type.tuple) = d->type;
				}
			}
		}
	}
	if (!generic) {
		if (!type_resolve(tr, &f->ret_type, f->ret_type.where)) {
			success = false;
			goto ret;
		}
	}
	*ret_type = f->ret_type;

	if (ret_type->kind == TYPE_TYPE) {
		/* 
		   a function which returns a type but has non-constant parameters is weird...
		   but might be useful, so let's warn
		*/
		arr_foreach(f->params, Declaration, param) {
			if (!(param->flags & DECL_IS_CONST)) {
				warn_print(param->where, "Non-constant parameter in function which returns Type. (You can't call functions which return types at run-time, y'know)");
				break;
			}
		}
	}

 ret:
	arr_remove_lasta(&tr->blocks, tr->allocr);
	tr->block = prev_block;
	/* cleanup */
	if (entered_fn) {
		fn_exit(f);
		tr->fn = prev_fn;
	}
	return success;
}

static bool type_of_ident(Typer *tr, Location where, Identifier i, Type *t) {
	t->flags = 0;
	IdentDecl *decl = ident_decl(i);
	if (!decl) {
		char *s = ident_to_str(i);
		err_print(where, "Undeclared identifier: %s", s);
		free(s);
		return false;
	}
	switch (decl->kind) {
	case IDECL_DECL: {
		Declaration *d = decl->decl;
		bool captured = false;
		if (decl->scope != NULL) {
			/* go back through scopes */
			for (Block **block = arr_last(tr->blocks); *block && *block != decl->scope; --block) {
				if ((*block)->flags & BLOCK_IS_FN) {
					captured = true;
					break;
				}
			}
		}
		if (captured && !(d->flags & DECL_IS_CONST)) {
			err_print(where, "Variables cannot be captured into inner functions (but constants can).");
			return false;
		}
		/* are we inside this declaration? */
		typedef Declaration *DeclarationPtr;
		arr_foreach(tr->in_decls, DeclarationPtr, in_decl) {
			if (d == *in_decl) {
				assert(d->flags & DECL_HAS_EXPR); /* we can only be in decls with an expr */
				if (d->expr.kind != EXPR_FN) { /* it's okay if a function references itself */
					/* if we've complained about it before when we were figuring out the type, don't complain again */
					if (!(d->flags & DECL_ERRORED_ABOUT_SELF_REFERENCE)) {
						char *s = ident_to_str(i);
						err_print(where, "Use of identifier %s in its own declaration.", s);
						free(s);
						info_print(d->where, "Declaration was here.");
						d->flags |= DECL_ERRORED_ABOUT_SELF_REFERENCE;
					}
					return false;
				}
			}
		}
	
		if (d->flags & DECL_FOUND_TYPE) {
			*t = *decl_type_at_index(d, decl_ident_index(d, i));
			return true;
		} else {
			if ((d->flags & DECL_HAS_EXPR) && (d->expr.kind == EXPR_FN)) {
				/* allow using a function before declaring it */
				if (!type_of_fn(tr, d->expr.fn, t, 0)) return false;
				return true;
			} else {
				if (location_after(d->where, where)) {
					char *s = ident_to_str(i);
					err_print(where, "Use of identifier %s before its declaration.\nNote that it is only possible to use a constant function before it is directly declared (e.g. x ::= fn() {}).", s);
					info_print(d->where, "%s will be declared here.", s);
					free(s);
				} else {
					/* let's type the declaration, and redo this (for evaling future functions) */
					if (!types_decl(tr, d)) return false;
					return type_of_ident(tr, where, i, t);
				}
				return false;
			}
		}
	} break;
	case IDECL_EXPR: {
		Expression *e = decl->expr;
		/* are we inside this expression? */
		typedef Expression *ExpressionPtr;
		arr_foreach(tr->in_expr_decls, ExpressionPtr, in_e) {
			if (*in_e == e) {
				char *s = ident_to_str(i);
				err_print(where, "Use of identifier %s in its own declaration.", s);
				free(s);
				return false;
			}
		}
		
		switch (e->kind) {
		case EXPR_EACH:
			if (i == e->each->index) {
				t->kind = TYPE_BUILTIN;
				t->builtin = BUILTIN_I64;
			} else {
				assert(i == e->each->value);
				*t = e->each->type;
			}
			break;
		default: assert(0); return false;
		}
	} break;
	}
	return true;
}

/* fixes the type (replaces [5+3]int with [8]int, etc.) */
static bool type_resolve(Typer *tr, Type *t, Location where) {
	Evaluator *ev = tr->evalr;
	if (t->flags & TYPE_IS_RESOLVED) return true;
	t->was_expr = NULL;
	switch (t->kind) {
	case TYPE_ARR: {
		/* it's an array */
		Value val;
		Expression *n_expr = t->arr.n_expr;
		if (!types_expr(tr, n_expr)) return false;
		if (n_expr->type.kind == TYPE_UNKNOWN) {
			err_print(n_expr->where, "Cannot determine type of array size at compile time.");
			return false;
		}
		if (n_expr->type.kind != TYPE_BUILTIN || !type_builtin_is_int(n_expr->type.builtin)) {
			char *s = type_to_str(&n_expr->type);
			err_print(n_expr->where, "Cannot use type %s as the size of an array (it's not an integer type).", s);
			free(s);
			return false;
		}
		if (!eval_expr(ev, n_expr, &val))
			return false;

		U64 size;
		if (type_builtin_is_signed(n_expr->type.builtin)) {
		    I64 ssize = val_to_i64(&val, n_expr->type.builtin);
			if (ssize < 0) {
				err_print(t->arr.n_expr->where, "Negative array length (" I64_FMT ")", ssize);
				return false;
			}
			size = (U64)ssize;
		} else {
			size = val_to_u64(&val, n_expr->type.builtin);
		}
		t->arr.n = (U64)size;
		if (!type_resolve(tr, t->arr.of, where))
			return false;
	} break;
	case TYPE_FN:
		arr_foreach(t->fn.types, Type, child_type) {
			if (!type_resolve(tr, child_type, where))
				return false;
		}
		break;
	case TYPE_TUPLE:
		arr_foreach(t->tuple, Type, child_type) {
			if (!type_resolve(tr, child_type, where))
				return false;
		}
		break;
	case TYPE_PTR:
		if (!type_resolve(tr, t->ptr, where))
			return false;
		break;
	case TYPE_SLICE:
		if (!type_resolve(tr, t->slice, where))
			return false;
		break;
	case TYPE_STRUCT:
		arr_foreach(t->struc->fields, Field, f) {
			if (!type_resolve(tr, f->type, where))
				return false;
		}
		break;
	case TYPE_EXPR: {
		Value typeval;
		if (!types_expr(tr, t->expr))
			return false;
		if (t->expr->type.kind != TYPE_TYPE) {
			err_print(where, "This expression is not a type, but it's being used as one.");
			return false;
		}
		Expression *expr = t->expr;
		if (!eval_expr(tr->evalr, t->expr, &typeval))
			return false;
		*t = *typeval.type;
		t->was_expr = expr;
		assert(t->flags & TYPE_IS_RESOLVED);
	} break;
	case TYPE_UNKNOWN:
	case TYPE_VOID:
	case TYPE_TYPE:
	case TYPE_BUILTIN:
		break;
	}
	assert(t->kind != TYPE_EXPR);
	t->flags |= TYPE_IS_RESOLVED;
	return true;
}



static bool type_can_be_truthy(Type *t) {
	assert(t->flags & TYPE_IS_RESOLVED);
	switch (t->kind) {
	case TYPE_VOID:
	case TYPE_TUPLE:
	case TYPE_ARR:
	case TYPE_TYPE:
	case TYPE_STRUCT:
		return false;
	case TYPE_FN:
	case TYPE_UNKNOWN:
	case TYPE_BUILTIN:
	case TYPE_PTR:
	case TYPE_SLICE:
		return true;
	case TYPE_EXPR:
		break;
	}
	assert(0);
	return false;
}

typedef enum {
			  STATUS_NONE,
			  STATUS_WARN,
			  STATUS_ERR
} Status;

static Status type_cast_status(Type *from, Type *to) {
	assert(from->flags & TYPE_IS_RESOLVED);
	assert(to->flags & TYPE_IS_RESOLVED);
	
	if (to->kind == TYPE_UNKNOWN)
		return STATUS_NONE;
	switch (from->kind) {
	case TYPE_UNKNOWN: return STATUS_NONE;
	case TYPE_STRUCT:
	case TYPE_TYPE:
	case TYPE_VOID:
		return STATUS_ERR;
	case TYPE_BUILTIN:
		switch (from->builtin) {
		case BUILTIN_I8:
		case BUILTIN_U8:
		case BUILTIN_I16:
		case BUILTIN_U16:
		case BUILTIN_I32:
		case BUILTIN_U32:
		case BUILTIN_I64:
		case BUILTIN_U64:
			switch (to->kind) {
			case TYPE_BUILTIN:
			case TYPE_UNKNOWN:
				return STATUS_NONE;
			case TYPE_PTR:
				return STATUS_WARN;
			case TYPE_FN:
			case TYPE_TYPE:
			case TYPE_TUPLE:
			case TYPE_SLICE:
			case TYPE_STRUCT:
			case TYPE_ARR:
			case TYPE_VOID:
				return STATUS_ERR;
			case TYPE_EXPR:
				assert(0);
			}
			break;
		case BUILTIN_F32:
		case BUILTIN_F64:
			if (to->kind == TYPE_BUILTIN && to->builtin != BUILTIN_CHAR)
				return STATUS_NONE;
			return STATUS_ERR;
		case BUILTIN_CHAR:
			if (to->kind == TYPE_BUILTIN && type_builtin_is_int(to->builtin))
				return STATUS_NONE;
			return STATUS_ERR;
		case BUILTIN_BOOL:
			return type_can_be_truthy(to) ? STATUS_NONE : STATUS_ERR;
		}
		break;
	case TYPE_TUPLE: return STATUS_ERR;
	case TYPE_FN:
		if (to->kind == TYPE_PTR || to->kind == TYPE_FN)
			return STATUS_WARN;
		return STATUS_ERR;
	case TYPE_PTR:
		if (to->kind == TYPE_BUILTIN && type_builtin_is_int(to->builtin))
			return STATUS_WARN;
		if (to->kind == TYPE_PTR)
			return STATUS_NONE;
		if (to->kind == TYPE_FN)
			return STATUS_WARN;
		/* TODO: Cast from ptr to arr */
		return STATUS_ERR;
	case TYPE_ARR:
		return STATUS_ERR;
	case TYPE_SLICE:
		if (to->kind == TYPE_PTR && type_eq(from->slice, to->ptr))
			return STATUS_NONE;
	    return STATUS_ERR;
	case TYPE_EXPR:
		break;
	}
	assert(0);
	return STATUS_ERR;
}

static bool arg_is_const(Expression *arg, Constness constness) {
	switch (constness) {
	case CONSTNESS_NO: return false;
	case CONSTNESS_SEMI: return expr_is_definitely_const(arg);
	case CONSTNESS_YES: return true;
	}
	assert(0);
	return false;
}


/* MUST be called after type_of_fn. */
/* pass NULL for instance if this isn't an instance */
static bool types_fn(Typer *tr, FnExpr *f, Type *t, Location where,
					 Instance *instance) {
	FnExpr *prev_fn = tr->fn;
	bool success = true;
	bool entered_fn = false;
	Expression *ret_expr;
	Type *ret_type;
	bool has_named_ret_vals;
	assert(t->kind == TYPE_FN);
	if (instance) {
		f = &instance->fn;
	} else {
		if (t->fn.constness)
			return true; /* don't type function body yet; we need to do that for every instance */
	}
	
	tr->fn = f;
	if (!fn_enter(f, SCOPE_CHECK_REDECL)) {
		success = false;
		goto ret;
	}
	entered_fn = true;
	if (!types_block(tr, &f->body)) {
		success = false;
		goto ret;
	}
	ret_expr = f->body.ret_expr;
	ret_type = t->fn.types;
	has_named_ret_vals = f->ret_decls != NULL;
	if (ret_expr) {
		if (!type_eq(ret_type, &ret_expr->type)) {
			char *got = type_to_str(&ret_expr->type);
			char *expected = type_to_str(ret_type);
			err_print(ret_expr->where, "Returning type %s, but function returns type %s.", got, expected);
			if (!instance) /* where will only actually be at the function declaration if it isn't
							  an instance. otherwise, where will be at the calling site, which will already be
							  printed */
				info_print(where, "Function declaration is here.");
			free(got); free(expected);
			success = false;
			goto ret;
		}
	} else if (ret_type->kind != TYPE_VOID && !has_named_ret_vals) {
		Statement *stmts = f->body.stmts;
		if (arr_len(stmts)) {
			Statement *last_stmt = (Statement *)stmts + (arr_len(stmts) - 1);
			if (last_stmt->kind == STMT_RET) {
				/*
				  last statement is a return, so it doesn't matter that the function has no return value
				  ideally this would handle if foo { return 5; } else { return 6; }
				*/
				success = true;
				goto ret;
			}
		}
		/* TODO: this should really be at the closing brace, and not the function declaration */
		char *expected = type_to_str(ret_type);
		err_print(f->body.end, "No return value in function which returns %s.", expected);
		free(expected);
		info_print(where, "Function was declared here:");
		success = false;
		goto ret;
	}
 ret:
	if (entered_fn)
		fn_exit(f);
	tr->fn = prev_fn;
	return success;
}

/* puts a dynamic array of the parameter indices of the arguments into param_indices. */
static bool call_arg_param_order(Allocator *allocr, FnExpr *fn, Location fn_where, Type *fn_type, Argument *args, Location where, U16 **param_indices) {
	size_t nparams = arr_len(fn_type->fn.types)-1;
	size_t nargs = arr_len(args);
	if (nargs > nparams) {
		err_print(where, "Expected at most %lu arguments to function, but got %lu.",
				  nparams, nargs);
		return false;
	}
	int p = 0; /* counter for sequential parameters */

	Declaration *last_param_without_default_value = NULL;
	arr_foreach(fn->params, Declaration, param) {
		if (!(param->flags & DECL_HAS_EXPR)) {
			last_param_without_default_value = param;
		}
	}
	Declaration *param = fn->params;
	size_t ident_idx = 0;
	U16 *order = NULL;
	arr_foreach(args, Argument, arg) {
		bool named = arg->name != NULL;
		int param_idx = -1;
		if (named) {
			/* named argument */
			int index = 0;
			bool found = false;
			arr_foreach(fn->params, Declaration, pa) {
				arr_foreach(pa->idents, Identifier, id) {
					if (*id == arg->name) {
						found = true;
						break;
					}
					++index;
				}
				if (found) break;
			}
			if (!found) {
				char *s = ident_to_str(arg->name);
				err_print(arg->where, "Argument '%s' does not appear in declaration of function.", s);
				free(s);
				info_print(fn_where, "Declaration is here.");
				return false;
			}
			param_idx = index;
		} else {
			if (param > (Declaration *)arr_last(fn->params)) {
				err_print(arg->where, "Too many arguments to function!");
				info_print(fn_where, "Declaration is here.");
				return false;
			}
		
			if ((param->flags & (DECL_HAS_EXPR | DECL_INFER)) && param < last_param_without_default_value) {
				/* this param must be named; so this is referring to a later parameter */
				--arg;
			} else {
				param_idx = p;
			}
		}

		if (param_idx != -1) {
			*(U16 *)arr_adda(&order, allocr) = (U16)param_idx;
		}

		if (!named) {
			/* sequential order of parameters */
			++p;
			++ident_idx;
			if (ident_idx == arr_len(param->idents)) {
				++param;
				ident_idx = 0;
			}
		}
	}
	*param_indices = order;
	return true;
}

static bool types_expr(Typer *tr, Expression *e) {
	if (e->flags & EXPR_FOUND_TYPE) return true;
	Type *t = &e->type;
	t->flags = 0;
	t->was_expr = NULL;
	t->kind = TYPE_UNKNOWN; /* default to unknown type (in the case of an error) */
	e->flags |= EXPR_FOUND_TYPE; /* even if failed, pretend we found the type */
	switch (e->kind) {
	case EXPR_FN: {
		if (!type_of_fn(tr, e->fn, &e->type, 0))
			return false;
		if (fn_has_any_const_params(e->fn)) {
			HashTable z = {0};
			e->fn->instances = z;
		} else {
			if (!types_fn(tr, e->fn, &e->type, e->where, NULL))
				return false;
		}
	} break;
	case EXPR_LITERAL_INT:
	    t->kind = TYPE_BUILTIN;
		t->builtin = BUILTIN_I64;
		t->flags |= TYPE_IS_FLEXIBLE | TYPE_IS_RESOLVED;
		break;
	case EXPR_LITERAL_STR:
		t->kind = TYPE_SLICE;
		t->slice = typer_malloc(tr, sizeof *t->slice);
		t->slice->flags = TYPE_IS_RESOLVED;
		t->slice->was_expr = NULL;
		t->slice->kind = TYPE_BUILTIN;
		t->slice->builtin = BUILTIN_CHAR;
		t->flags |= TYPE_IS_RESOLVED;
		break;
	case EXPR_LITERAL_FLOAT:
		t->kind = TYPE_BUILTIN;
		t->builtin = BUILTIN_F32;
		t->flags |= TYPE_IS_FLEXIBLE | TYPE_IS_RESOLVED;
		break;
	case EXPR_LITERAL_BOOL:
		t->kind = TYPE_BUILTIN;
		t->builtin = BUILTIN_BOOL;
		t->flags |= TYPE_IS_RESOLVED;
		break;
	case EXPR_LITERAL_CHAR:
		t->kind = TYPE_BUILTIN;
		t->builtin = BUILTIN_CHAR;
		t->flags |= TYPE_IS_RESOLVED;
		break;
	case EXPR_EACH: {
		EachExpr *ea = e->each;
		*(Expression **)typer_arr_add(tr, &tr->in_expr_decls) = e;
		if (!each_enter(e)) return false;
		if (ea->flags & EACH_IS_RANGE) {
			/* TODO: allow user-defined numerical types */
			if (!types_expr(tr, ea->range.from)) return false;
			{
				Type *ft = &ea->range.from->type;
				if (ft->kind != TYPE_BUILTIN || !type_builtin_is_numerical(ft->builtin)) {
					char *s = type_to_str(ft);
					err_print(e->where, "from expression of each must be a builtin numerical type, not %s", s);
					free(s);
				}
			}
			if (ea->range.step) {
				if (!types_expr(tr, ea->range.step)) return false;
				Type *st = &ea->range.step->type;
				if (st->kind != TYPE_BUILTIN || !type_builtin_is_numerical(st->builtin)) {
					char *s = type_to_str(st);
					err_print(e->where, "step expression of each must be a builtin numerical type, not %s", s);
					free(s);
				}
			}
			if (ea->range.to) {
				if (!types_expr(tr, ea->range.to)) return false;
				Type *tt = &ea->range.to->type;
				if (tt->kind != TYPE_BUILTIN || !type_builtin_is_numerical(tt->builtin)) {
					char *s = type_to_str(tt);
					err_print(e->where, "to expression of each must be a builtin numerical type, not %s", s);
					free(s);
				}
			}

			if (!(ea->flags & EACH_ANNOTATED_TYPE)) {
			    ea->type = ea->range.from->type;
			}
			
			if (!type_eq(&ea->type, &ea->range.from->type)) {
				char *exp = type_to_str(&ea->type);
				char *got = type_to_str(&ea->range.from->type);
				err_print(e->where, "Type of each does not match the type of the from expression. Expected %s, but got %s.", exp, got);
				free(exp); free(got);
				return false;
			}
			
			if (ea->range.step && !type_eq(&ea->type, &ea->range.step->type)) {
				char *exp = type_to_str(&ea->type);
				char *got = type_to_str(&ea->range.step->type);
				err_print(e->where, "Type of each does not match the type of the step expression. Expected %s, but got %s.", exp, got);
				free(exp); free(got);
				return false;
			}
			
			if ((ea->type.flags & TYPE_IS_FLEXIBLE) && ea->range.step)
				ea->type = ea->range.step->type;
			
			if (ea->range.to && !type_eq(&ea->type, &ea->range.to->type)) {
				char *exp = type_to_str(&ea->type);
				char *got = type_to_str(&ea->range.to->type);
				err_print(e->where, "Type of each does not match the type of the to expression. Expected %s, but got %s.", exp, got);
				free(exp); free(got);
				return false;
			}
			
			if ((ea->type.flags & TYPE_IS_FLEXIBLE) && ea->range.to)
				ea->type = ea->range.to->type;
			ea->type.flags &= (TypeFlags)~(TypeFlags)TYPE_IS_FLEXIBLE;
		} else {
			if (!types_expr(tr, ea->of))
				return false;
			Type *iter_type = &ea->of->type;

			bool uses_ptr = false;
			if (iter_type->kind == TYPE_PTR) {
				uses_ptr = true;
				iter_type = iter_type->ptr;
			}
			switch (iter_type->kind) {
			case TYPE_SLICE:
				iter_type = iter_type->slice;
				break;
			case TYPE_ARR:
				iter_type = iter_type->arr.of;
				break;
			default: {
				char *s = type_to_str(&ea->of->type);
				err_print(e->where, "Cannot iterate over non-array non-slice type %s.", s);
				free(s);
				return false;
			}
			}
			Type ptr_type = {0};
			if (uses_ptr) {
				ptr_type.flags = TYPE_IS_RESOLVED;
				ptr_type.kind = TYPE_PTR;
				ptr_type.ptr = iter_type;
				iter_type = &ptr_type;
			}
			if (ea->flags & EACH_ANNOTATED_TYPE) {
				if (!type_eq(iter_type, &ea->type)) {
					char *exp = type_to_str(iter_type);
					char *got = type_to_str(&ea->type);
					err_print(e->where, "Expected to iterate over type %s, but it was annotated as iterating over type %s.");
					free(exp); free(got);
					return false;
				}
			} else ea->type = *iter_type;
		}
		if ((ea->flags & EACH_IS_RANGE) && ea->range.step) {
			Value *stepval = typer_malloc(tr, sizeof *ea->range.stepval);
			if (!eval_expr(tr->evalr, ea->range.step, stepval)) {
				info_print(ea->range.step->where, "Note that the step of an each loop must be a compile-time constant.");
				return false;
			}
			val_cast(stepval, &ea->range.step->type, stepval, &ea->type);
			ea->range.stepval = stepval;
		}
		
		arr_remove_lasta(&tr->in_expr_decls, tr->allocr);
		
		if (!types_block(tr, &ea->body)) return false;
		each_exit(e);
		
		if (ea->body.ret_expr) {
			*t = ea->body.ret_expr->type;
		} else {
			t->kind = TYPE_VOID;
			t->flags |= TYPE_IS_RESOLVED;
		}
	} break;
	case EXPR_IDENT: {
		if (!type_of_ident(tr, e->where, e->ident, t)) return false;
	} break;
	case EXPR_CAST: {
		CastExpr *c = &e->cast;
		if (!types_expr(tr, c->expr))
			return false;
		if (!type_resolve(tr, &c->type, e->where))
			return false;
		Status status = type_cast_status(&c->expr->type, &c->type);
		if (status != STATUS_NONE) {
			char *from = type_to_str(&c->expr->type);
			char *to = type_to_str(&c->type);
			if (status == STATUS_ERR)

				err_print(e->where, "Cannot cast from type %s to %s.", from, to);
			else
				warn_print(e->where, "Casting from type %s to %s.", from, to);
			free(from);
			free(to);
			if (status == STATUS_ERR)
				return false;
		}
		*t = c->type;
	} break;
	case EXPR_NEW:
		if (!type_resolve(tr, &e->new.type, e->where))
			return false;
		if (e->new.n) {
			if (!types_expr(tr, e->new.n)) return false;
			if (e->new.n->type.kind != TYPE_BUILTIN || !type_builtin_is_int(e->new.n->type.builtin)) {
				char *got = type_to_str(&e->new.n->type);
				err_print(e->where, "Expected integer as second argument to new, but got %s.", got);
				free(got);
				return false;
			}
			t->kind = TYPE_SLICE;
			t->slice = &e->new.type;
		} else {
			t->kind = TYPE_PTR;
			t->ptr = &e->new.type;
		}
		break;
	case EXPR_IF: {
		IfExpr *i = &e->if_;
		IfExpr *curr = i;
		Type *curr_type = t;
		bool has_else = false;
		if (!types_block(tr, &curr->body))
			return false;
		if (curr->body.ret_expr) {
			*t = curr->body.ret_expr->type;
		} else {
			t->kind = TYPE_VOID;
			t->flags |= TYPE_IS_RESOLVED;
		}
		while (1) {
			if (curr->cond) {
				if (!types_expr(tr, curr->cond))
					return false;
				if (!type_can_be_truthy(&curr->cond->type)) {
					char *s = type_to_str(&curr->cond->type);
					err_print(curr->cond->where, "Type %s cannot be the condition of an if statement.", s);
					free(s);
					return false;
				}
			} else {
				has_else = true;
			}
			if (curr->next_elif) {
				IfExpr *nexti = &curr->next_elif->if_;
				Type *next_type = &curr->next_elif->type;
				curr->next_elif->flags |= EXPR_FOUND_TYPE;
				if (!types_block(tr, &nexti->body)) {
					return false;
				}
				if (nexti->body.ret_expr) {
					*next_type = nexti->body.ret_expr->type;
				} else {
					next_type->kind = TYPE_VOID;
					next_type->flags = TYPE_IS_RESOLVED;
					next_type->was_expr = NULL;
				}
				if (!type_eq(curr_type, next_type)) {
					char *currstr = type_to_str(curr_type);
					char *nextstr = type_to_str(next_type);
					err_print(curr->next_elif->where, "Mismatched types in if/elif/else chain. Previous block was of type %s, but this one is of type %s.", currstr, nextstr);
					free(currstr);
					free(nextstr);
					return false;
				}
				curr = nexti;
				
			} else {
				break;
			}
		}
		
		if (!has_else && t->kind != TYPE_VOID) {
			err_print(e->where, "Non-void if block with no else.");
			return false;
		}
	} break;
	case EXPR_WHILE: {
		WhileExpr *w = &e->while_;
		bool ret = true;
		if (w->cond && !types_expr(tr, w->cond))
			ret = false;
		if (!types_block(tr, &w->body))
			ret = false;
		if (!ret) return false;
		if (w->cond != NULL && w->body.ret_expr != NULL) {
			err_print(e->where, "A finite loop can't have a return expression (for an infinite loop, use while { ... }).");
			return false;
		}
		if (w->body.ret_expr)
			*t = w->body.ret_expr->type;
		else
			t->kind = TYPE_VOID;
	} break;
	case EXPR_CALL: {
		CallExpr *c = &e->call;
		c->instance = NULL;
		Expression *f = c->fn;
		FnExpr *fn_decl = NULL;
		if (!types_expr(tr, f)) return false;
		arr_foreach(c->args, Argument, arg) {
			if (!types_expr(tr, &arg->val))
				return false;
		}
		if (f->type.kind == TYPE_UNKNOWN) {
			e->type.kind = TYPE_UNKNOWN;
			return true;
		}
		if (f->type.kind != TYPE_FN) {
			char *type = type_to_str(&f->type);
			err_print(e->where, "Calling non-function (type %s).", type);
			return false;
		}
		Type *ret_type = f->type.fn.types;
		Type *param_types = ret_type + 1;
		Argument *args = c->args;
		size_t nparams = arr_len(f->type.fn.types) - 1;
		size_t nargs = arr_len(c->args);
		Expression *arg_exprs = NULL;
		arr_set_lena(&arg_exprs, nparams, tr->allocr);
		bool *params_set = nparams ? typer_calloc(tr, nparams, sizeof *params_set) : NULL;
		if (f->kind == EXPR_IDENT) {
			IdentDecl *decl = ident_decl(f->ident);
			assert(decl);
			if (decl->kind == IDECL_DECL) {
				if (decl->decl->flags & DECL_HAS_EXPR) {
					Expression *expr = &decl->decl->expr;
					if (expr->kind == EXPR_FN)
						fn_decl = decl->decl->expr.fn;
				}
			}
		}

		if (fn_decl) {
			U16 *order;
			if (!call_arg_param_order(tr->allocr, fn_decl, ident_decl(f->ident)->decl->where, &f->type, c->args, e->where, &order))
				return false;
			size_t arg;
			for (arg = 0; arg < nargs; ++arg) {
				U16 idx = order[arg];
				Expression expr = args[arg].val;
				arg_exprs[idx] = expr;
				if (params_set[idx]) {
					Declaration *param = fn_decl->params;
					Identifier *ident;
				    for (Declaration *end = arr_end(fn_decl->params); param < end; ++param) {
						ident = param->idents;
						for (Identifier *iend = arr_end(param->idents); ident != iend; ++ident) {
							if (idx == 0)
								goto dblbreak;
							--idx;
						}
					}
					assert(0);
				dblbreak:;
					char *s = ident_to_str(*ident);
					err_print(args[arg].where, "Argument #%lu (%s) set twice in function call.", idx+1, s);
					free(s);
					return false;
				}
				params_set[idx] = true;
			}
			arr_cleara(&order, tr->allocr);
		} else {
			if (nargs != nparams) {
				err_print(e->where, "Expected %lu arguments to function call, but got %lu.", (unsigned long)nparams, (unsigned long)nargs);
				return false;
			}
			for (size_t p = 0; p < nargs; ++p) {
				if (args[p].name) {
					err_print(args[p].where, "You can only use named arguments if you directly call a function.");
				}
				arg_exprs[p] = args[p].val;
				params_set[p] = true;
			}
		}

		FnType *fn_type = &f->type.fn;
		for (size_t i = 0; i < nparams; ++i) {
			if (!params_set[i]) {
				size_t index = 0;
				assert(fn_decl); /* we can only miss an arg if we're using named/optional args */
				
				arr_foreach(fn_decl->params, Declaration, param) {
					bool is_required = !(param->flags & (DECL_HAS_EXPR|DECL_INFER));
					int ident_idx = 0;

					arr_foreach(param->idents, Identifier, ident) {
						if (index == i) {
							if (is_required) {
								char *s = ident_to_str(*ident);
								err_print(e->where, "Argument %lu (%s) not set in function call.", 1+(unsigned long)i, s);
								free(s);
								return false;
							} else {
								if (!fn_type->constness) {
									/* default arg */
									assert(param->expr.kind == EXPR_VAL); /* evaluated in type_of_fn */
									arg_exprs[i].kind = EXPR_VAL;
									arg_exprs[i].flags = param->expr.flags;
									arg_exprs[i].type = param->type;
									arg_exprs[i].val = param->expr.val;
								}
							}
						}
						++ident_idx;
						++index;
					}
				}
			}
		}
		c->arg_exprs = arg_exprs;
		FnExpr *original_fn = NULL;
		Type table_index_type = {0};
		Value table_index = {0};
		FnExpr fn_copy;
		Copier cop = copier_create(tr->allocr, tr->block);
		if (fn_type->constness) {
			/* evaluate compile-time arguments + add an instance */
			
			
			/* the function had better be a compile time constant if it has constant params */
			Value fn_val = {0};
			if (!eval_expr(tr->evalr, f, &fn_val))
				return false;

			FnExpr *fn = fn_val.fn;
			/* fn is the instance, original_fn is not */
		    original_fn = fn;

			copy_fn_expr(&cop, &fn_copy, fn, false);
			fn = &fn_copy;
			/* keep track of the declaration */
			Declaration *param_decl = fn->params;
			size_t ident_idx = 0;
			size_t i = 0;

			Type **arg_types = NULL;
			Type **decl_types = NULL;
			Identifier *inferred_idents = NULL;
			
			arr_foreach(fn->params, Declaration, param) {
				arr_foreach(param->idents, Identifier, ident) {
					if (param->flags & DECL_INFER) {
						*(Identifier *)typer_arr_add(tr, &inferred_idents) = *ident;
					} else if ((param->flags & DECL_ANNOTATES_TYPE)
							   && !(param->flags & DECL_HAS_EXPR)) {
						
						if (param->type.kind == TYPE_TUPLE)
							err_print(param->where, "Parameters cannot have tuple types.");
						
						Type **p = typer_arr_add(tr, &decl_types);
						*p = &param->type;
						Type **q = typer_arr_add(tr, &arg_types);
						*q = &arg_exprs[i].type;
					}
					++i;
				}
			}

			size_t ninferred_idents = arr_len(inferred_idents);
			if (ninferred_idents) {
				Value *inferred_vals;
				Type *inferred_types;
				size_t inferred_vals_size = ninferred_idents * sizeof *inferred_vals;
				inferred_vals = typer_malloc(tr, inferred_vals_size);
				size_t inferred_types_size = ninferred_idents * sizeof *inferred_types;
				inferred_types = typer_malloc(tr, inferred_types_size);
				
				if (!infer_ident_vals(tr, decl_types, arg_types, inferred_idents, inferred_vals, inferred_types))
					return false;

				arr_cleara(&inferred_idents, tr->allocr);
				
				{
					Type *type = inferred_types;
					for (i = 0; i < ninferred_idents; ++i) {
						if (type->kind == TYPE_UNKNOWN) {
							long counter = (long)i;
							Declaration *decl = fn->params;
							while (1) {
								counter -= (long)arr_len(decl->idents);
								if (counter < 0) break;
								++decl;
							}
							err_print(decl->where, "Could not infer value of declaration.");
							info_print(e->where, "While processing this call");
							return false;
						}
						++type;
					}
				}
				i = 0;
				arr_foreach(fn->params, Declaration, param) {
					if (param->flags & DECL_INFER) {
						Value *val = &inferred_vals[i];
						Type *type = &inferred_types[i];
						/* if we have an inferred type argument, it shouldn't be flexible */
						if (type->kind == TYPE_TYPE)
							val->type->flags &= (TypeFlags)~(TypeFlags)TYPE_IS_FLEXIBLE;
						param->val = *val;
						param->type = *type;
						param->flags |= DECL_FOUND_VAL | DECL_FOUND_TYPE;
						++i;
					}
				}
				allocr_free(tr->allocr, inferred_vals, inferred_vals_size);
				allocr_free(tr->allocr, inferred_types, inferred_types_size);
			}
			


			i = 0;
			
			
			table_index_type.flags = TYPE_IS_RESOLVED;
			table_index_type.kind = TYPE_TUPLE;
			table_index_type.tuple = NULL;
			Type *u64t = typer_arr_add(tr, &table_index_type.tuple);
			u64t->was_expr = NULL;
			u64t->flags = TYPE_IS_RESOLVED;
			u64t->kind = TYPE_BUILTIN;
			u64t->builtin = BUILTIN_U64;
			table_index.tuple = NULL;
			/* we need to keep table_index's memory around because instance_table_add makes a copy of it to compare against. */
		    Value *which_are_const_val = typer_arr_add(tr, &table_index.tuple);
			U64 *which_are_const = &which_are_const_val->u64;
			*which_are_const = 0;
			int semi_const_index = 0;
			/* eval compile time arguments */
			for (i = 0; i < nparams; ++i) {
				bool should_be_evald = arg_is_const(&arg_exprs[i], fn_type->constness[i]);
				if (should_be_evald) {
					if (params_set[i]) {
						Expression *expr = &arg_exprs[i];
						Value *arg_val = typer_arr_add(tr, &table_index.tuple);
						if (!eval_expr(tr->evalr, expr, arg_val)) {
							if (tr->evalr->enabled) {
								info_print(arg_exprs[i].where, "(error occured while trying to evaluate compile-time argument, argument #%lu)", 1+(unsigned long)i);
							}
							return false;
						}
					
						Type *type = &expr->type;
						*(Type *)typer_arr_add(tr, &table_index_type.tuple) = *type;
				
						arg_exprs[i].kind = EXPR_VAL;
						arg_exprs[i].flags = EXPR_FOUND_TYPE;
						copy_val(tr->allocr, &arg_exprs[i].val, arg_val, type);
						arg_exprs[i].val = *arg_val;
						copy_val(tr->allocr, &param_decl->val, arg_val, type);
						param_decl->flags |= DECL_FOUND_VAL;
						if (!(param_decl->flags & DECL_ANNOTATES_TYPE)) {
							param_decl->type = *type;
						}
					} else {
						/* leave gap for this (default argument) */
						typer_arr_add(tr, &table_index.tuple);
						typer_arr_add(tr, &table_index_type.tuple);
					}
				}
				
				if (fn_type->constness[i] == CONSTNESS_SEMI) {
					if (semi_const_index >= 64) {
						err_print(f->where, "You can't have more than 64 semi-constant arguments to a function at the moment (sorry).");
						return false;
					}
					*which_are_const |= ((U64)1) << semi_const_index;
				}
				if (fn_type->constness[i] == CONSTNESS_SEMI) {
					++semi_const_index;
				}
				++ident_idx;
				if (ident_idx >= arr_len(param_decl->idents)) {
					ident_idx = 0;
					++param_decl;
				}
			}
			/* type params, return declarations, etc */
			if (!type_of_fn(tr, &fn_copy, &f->type, TYPE_OF_FN_IS_INSTANCE))
				return false;
			
			/* deal with default arguments */
			i = 0;
			arr_foreach(fn->params, Declaration, param) {
				arr_foreach(param->idents, Identifier, ident) {
					if (!params_set[i]) {
						if (param->flags & DECL_INFER) {
							arg_exprs[i].kind = EXPR_VAL;
							arg_exprs[i].flags = EXPR_FOUND_TYPE;
							arg_exprs[i].type = table_index_type.tuple[i+1] = param_types[i] = param->type;
							arg_exprs[i].val = table_index.tuple[i+1] = param->val;
							params_set[i] = true;
							++i;
							continue;
						}
						assert(param->flags & DECL_HAS_EXPR);
						assert(param->expr.kind == EXPR_VAL); /* this was done by type_of_fn */
						arg_exprs[i] = param->expr;
						/* make sure value is copied */
						copy_val(tr->allocr, &arg_exprs[i].val, &param->expr.val, &param->expr.type);
						Value *arg_val = &table_index.tuple[i+1];
						copy_val(tr->allocr, arg_val, &param->expr.val, &param->expr.type);
						table_index_type.tuple[i+1] = param->expr.type;
						params_set[i] = true;
					}
					++i;
				}
				
			}
			
			ret_type = f->type.fn.types;
			param_types = ret_type + 1;
		}
		
		/* check types of arguments */
		for (size_t p = 0; p < nparams; ++p) {
			Expression *arg = &arg_exprs[p];
			Type *expected = &param_types[p];
			Type *got = &arg->type;
			if (!type_eq(expected, got)) {
				char *estr = type_to_str(expected);
				char *gstr = type_to_str(got);
				err_print(arg->where, "Expected type %s as argument to function, but got %s.", estr, gstr);
				return false;
			}
		}
		
		if (fn_type->constness) {
			bool instance_already_exists;
			c->instance = instance_table_adda(tr->allocr, &original_fn->instances, table_index, &table_index_type, &instance_already_exists);
			if (instance_already_exists) {
				arr_cleara(&table_index_type.tuple, tr->allocr);
				arr_cleara(&table_index.tuple, tr->allocr);
			} else {
				copy_block(&cop, &fn_copy.body, &original_fn->body);
				c->instance->fn = fn_copy;
				/* fix parameter and return types (they were kind of problematic before, because we didn't know about the instance) */
				c->instance->c.id = original_fn->instances.n; /* let's help cgen out and assign an ID to this */
				/* type this instance */
				
				/* if anything happens, make sure we let the user know that this happened while generating a fn */
				ErrCtx *err_ctx = e->where.ctx;
				*(Location *)typer_arr_add(tr, &err_ctx->instance_stack) = e->where;
				bool success = types_fn(tr, &c->instance->fn, &f->type, e->where, c->instance);
				arr_remove_lasta(&err_ctx->instance_stack, tr->allocr);
				if (!success) return false;
				arr_cleara(&table_index_type.tuple, tr->allocr);
			}
		}

		*t = *ret_type;
	} break;
	case EXPR_BLOCK: {
		Block *b = &e->block;
		if (!types_block(tr, b))
			return false;
		if (b->ret_expr) {
			*t = b->ret_expr->type;
		} else {
			t->kind = TYPE_VOID;
		}
	} break;
	case EXPR_C: {
		Expression *code = e->c.code;
		if (!types_expr(tr, code))
			return false;
		if (code->type.kind != TYPE_SLICE
			|| !type_is_builtin(code->type.slice, BUILTIN_CHAR)) {
			char *s = type_to_str(&code->type);
			err_print(e->where, "Argument to #C directive must be a string, but got type %s.");
			free(s);
			return false;
		}
		Value code_val;
		if (!eval_expr(tr->evalr, code, &code_val))
			return false;
		code->val = code_val;
		code->kind = EXPR_VAL;
		t->kind = TYPE_UNKNOWN;
	} break;
	case EXPR_DSIZEOF:
	case EXPR_DALIGNOF: {
		Expression *of = e->kind == EXPR_DSIZEOF ? e->dsizeof.of : e->dalignof.of;
		if (!types_expr(tr, of))
			return false;
		if (e->dsizeof.of->type.kind == TYPE_TYPE) {
			Value val;
			if (!eval_expr(tr->evalr, of, &val))
				return false;
			e->val.i64 = (I64)compiler_sizeof(val.type);
		} else {
			e->val.i64 = (I64)compiler_sizeof(&of->type);
		}
		e->kind = EXPR_VAL;
		t->kind = TYPE_BUILTIN;
		t->builtin = BUILTIN_I64;
	} break;
	case EXPR_UNARY_OP: {
		Expression *of = e->unary.of;
		Type *of_type = &of->type;
		if (!types_expr(tr, e->unary.of)) return false;
		if (of_type->kind == TYPE_UNKNOWN) {
			return true;
		}
		switch (e->unary.op) {
		case UNARY_MINUS:
			if (of_type->kind != TYPE_BUILTIN || !type_builtin_is_numerical(of_type->builtin)) {
				char *s = type_to_str(of_type);
				err_print(e->where, "Cannot apply unary - to non-numerical type %s.", s);
				free(s);
				return false;
			}
			if (!type_builtin_is_signed(of_type->builtin)) {
				char *s = type_to_str(of_type);
				warn_print(e->where, "Applying unary - to unsigned type %s may cause overflow.", s);
				free(s);
			}
			*t = *of_type;
			break;
		case UNARY_ADDRESS:
			if (of_type->kind == TYPE_TYPE) {
				/* oh it's a type! */
				t->kind = TYPE_TYPE;
				break;
			}
			if (!expr_must_lval(of)) {
				return false;
			}
			if (of_type->kind == TYPE_TUPLE) {
				err_print(e->where, "Cannot take address of tuple.");
				return false;
			}
			t->kind = TYPE_PTR;
			t->ptr = typer_malloc(tr, sizeof *t->ptr);
			*t->ptr = *of_type;
			break;
		case UNARY_DEREF:
			if (of_type->kind != TYPE_PTR) {
				char *s = type_to_str(of_type);
				err_print(e->where, "Cannot dereference non-pointer type %s.", s);
				free(s);
				return false;
			}
			
			*t = *of_type->ptr;
			break;
		case UNARY_DEL:
			if (of_type->kind != TYPE_PTR && of_type->kind != TYPE_SLICE) {
				char *s = type_to_str(of_type);
				err_print(e->where, "Cannot delete non-pointer, non-slice type %s.", s);
				free(s);
				return false;
			}
			t->kind = TYPE_VOID;
			break;
		case UNARY_NOT:
			if (!type_can_be_truthy(of_type)) {
				char *s = type_to_str(of_type);
				err_print(e->where, "Type '%s' cannot be truthy, so the not operator cannot be applied to it.", s);
				free(s);
				return false;
			}
			t->kind = TYPE_BUILTIN;
			t->builtin = BUILTIN_BOOL;
			break;
		case UNARY_LEN:
			t->kind = TYPE_BUILTIN;
			t->builtin = BUILTIN_I64;
			if (of_type->kind != TYPE_SLICE || of_type->kind != TYPE_ARR) {
				char *s = type_to_str(of_type);
				err_print(e->where, "Cannot get length of non-array, non-slice type %s.", s);
				free(s);
				return false;
			}
			break;
		}
	} break;
	case EXPR_BINARY_OP: {
		Expression *lhs = e->binary.lhs;
		Expression *rhs = e->binary.rhs;
		Type *lhs_type = &lhs->type;
		Type *rhs_type = &rhs->type;
			   
		BinaryOp o = e->binary.op;
		if (o != BINARY_DOT) {
			if (!types_expr(tr, lhs)
				|| !types_expr(tr, rhs))
				return false;
			if (lhs_type->kind == TYPE_UNKNOWN || rhs_type->kind == TYPE_UNKNOWN) {
				return true;
			}
		}
		switch (o) {
		case BINARY_SET:
		case BINARY_SET_ADD:
		case BINARY_SET_SUB:
		case BINARY_SET_MUL:
		case BINARY_SET_DIV:
			if (!expr_must_lval(e->binary.lhs)) {
				return false;
			}
			/* fallthrough */
		case BINARY_ADD:
		case BINARY_SUB:
		case BINARY_MUL:
		case BINARY_DIV:
		case BINARY_LT:
		case BINARY_GT:
		case BINARY_LE:
		case BINARY_GE:
		case BINARY_EQ:
		case BINARY_NE: {
			bool valid = false;
			assert(lhs_type->flags & TYPE_IS_RESOLVED);
			assert(rhs_type->flags & TYPE_IS_RESOLVED);
		    
			
			if (o == BINARY_SET) {
				valid = type_eq(lhs_type, rhs_type);
				if (lhs_type->kind == TYPE_TYPE) {
					err_print(e->where, "Cannot set type.");
					return false;
				}
			} else {
				/* numerical binary ops */
				if (lhs_type->kind == TYPE_BUILTIN && type_eq(lhs_type, rhs_type)) {
					/* int + int, etc. */
					valid = true;
				}
				if (o == BINARY_ADD || o == BINARY_SUB || o == BINARY_SET_ADD || o == BINARY_SET_SUB) {
					if (lhs_type->kind == TYPE_PTR &&
						rhs_type->kind == TYPE_BUILTIN &&
						type_builtin_is_numerical(rhs_type->builtin)) {
						valid = true;
					}
				}
				if (o == BINARY_LT || o == BINARY_GT || o == BINARY_LE || o == BINARY_GE
					|| o == BINARY_EQ || o == BINARY_NE) {
					/* comparable types */
					if (type_eq(lhs_type, rhs_type)) {
						switch (lhs_type->kind) {
						case TYPE_PTR:
						case TYPE_BUILTIN: /* all builtins are comparable */
							valid = true;
						default:
							break;
						}
					}
				}
			}
			if (valid) {
				switch (o) {
				case BINARY_SET:
					/* type of x = y is always void */
					t->kind = TYPE_VOID;
					break;
				case BINARY_LT:
				case BINARY_GT:
				case BINARY_LE:
				case BINARY_GE:
				case BINARY_EQ:
				case BINARY_NE:
					t->kind = TYPE_BUILTIN;
					t->builtin = BUILTIN_BOOL;
					break;
				default: {
					int lhs_is_flexible = lhs_type->flags & TYPE_IS_FLEXIBLE;
					int rhs_is_flexible = rhs_type->flags & TYPE_IS_FLEXIBLE;
					if (lhs_is_flexible && rhs_is_flexible) {
						/* both flexible */
						*t = *lhs_type;
						if (rhs_type->builtin == BUILTIN_F32) {
							/* promote to float */
							t->builtin = BUILTIN_F32;
						}
						
					} else if (!lhs_is_flexible) {
						/* lhs inflexible, rhs ? */
						*t = *lhs_type;
					} else {
						/* lhs flexible, rhs ? */
						*t = *rhs_type;
					}
				} break;
				}
			}
			if (!valid) {
				char *s1, *s2;
				s1 = type_to_str(lhs_type);
				s2 = type_to_str(rhs_type);
				const char *op = binary_op_to_str(o);
				err_print(e->where, "Invalid types to operator %s: %s and %s", op, s1, s2);
				return false;
			}
			if (o == BINARY_SET_ADD ||
				o == BINARY_SET_SUB ||
				o == BINARY_SET_MUL ||
				o == BINARY_SET_DIV) {
				t->kind = TYPE_VOID; /* actually, it's just void */
			}
				
			break;
		}
		case BINARY_AT_INDEX:
			if ((lhs_type->kind == TYPE_ARR || lhs_type->kind == TYPE_SLICE) &&
				(rhs_type->kind != TYPE_BUILTIN || !type_builtin_is_numerical(rhs_type->builtin))) {
				err_print(e->where, "The index of an array must be a builtin numerical type.");
				return false;
			}
			switch (lhs_type->kind) {
			case TYPE_ARR:
				*t = *lhs_type->arr.of;
				break;
			case TYPE_SLICE:
				*t = *lhs_type->slice;
				break;
			case TYPE_PTR:
				lhs_type = lhs_type->ptr;
				if (lhs_type->kind != TYPE_STRUCT) break;
				/* fallthrough */
			case TYPE_STRUCT: {
				/* allow accessing struct members with a string */
				if (rhs_type->kind != TYPE_SLICE
					|| !type_is_builtin(rhs_type->slice, BUILTIN_CHAR)) {
					char *s = type_to_str(rhs_type);
					err_print(e->where, "Expected a string for struct member access with [], but got type %s.", s);
					return false;
				}
				Value field_name;
				
				/* replace with BINARY_DOT */
				e->binary.op = BINARY_DOT;
				bool is_field = false;
				if (!eval_expr(tr->evalr, rhs, &field_name)) return false;
				arr_foreach(lhs_type->struc->fields, Field, f) {
					if (ident_eq_str(f->name, field_name.slice.data)) {
						is_field = true;
						*t = *f->type;
						e->binary.field = f;
					}
				}
				if (!is_field) {
					char *fstr = err_malloc((size_t)(field_name.slice.n + 1));
					memcpy(fstr, field_name.slice.data, (size_t)field_name.slice.n);
					fstr[field_name.slice.n] = 0; /* null-terminate */
					char *typestr = type_to_str(lhs_type);
					err_print(e->where, "%s is not a field of structure %s.", fstr, typestr);
					free(fstr); free(typestr);
					return false;
				}
			} break;
			default: {
				char *s = type_to_str(lhs_type);
				err_print(e->where, "Trying to take index of non-array type %s.", s);
				free(s);
				return false;
			}
			}
			break;
		case BINARY_DOT: {
			if (!types_expr(tr, lhs)) return false;
			Type *struct_type = lhs_type;
			if (struct_type->kind == TYPE_PTR)
				struct_type = struct_type->ptr;
			if (rhs->kind != EXPR_IDENT) {
				err_print(rhs->where, "Expected identifier for struct member access, but got %s.",
						  expr_kind_to_str(rhs->kind));
				return false;
			}
			if (struct_type->kind == TYPE_STRUCT) {
				bool is_field = false;
				if (rhs->kind == EXPR_IDENT) {
					/* maybe accessing a field? */
					arr_foreach(struct_type->struc->fields, Field, f) {
						if (f->name == rhs->ident) {
							is_field = true;
							*t = *f->type;
							e->binary.field = f;
						}
					}
				}

				if (!is_field) {
					char *member = ident_to_str(rhs->ident);
					char *struc = type_to_str(struct_type);
					err_print(e->where, "%s is not a member of structure %s.", member, struc);
					return false;
				}
			} else if (struct_type->kind == TYPE_SLICE || struct_type->kind == TYPE_ARR) {
				if (!(rhs->kind == EXPR_IDENT && ident_eq_str(rhs->ident, "len"))) {
						
					Value field_name;
					if (!types_expr(tr, rhs)) return false;
					if (rhs_type->kind != TYPE_SLICE || !type_is_builtin(rhs_type->slice, BUILTIN_CHAR)) {
						err_print(e->where, "Invalid field of type %s.");
						return false;
						
					}
					if (!eval_expr(tr->evalr, rhs, &field_name)) return false;
					char *str = field_name.slice.data;
					if (field_name.slice.n != 3	|| strcmp(str, "len") != 0) {					
						char *fstr = err_malloc((size_t)(field_name.slice.n + 1));
						memcpy(fstr, field_name.slice.data, (size_t)field_name.slice.n);
						fstr[field_name.slice.n] = 0; /* null-terminate */
						char *typestr = type_to_str(lhs_type);
						err_print(e->where, "%s is not a field of type %s.", fstr, typestr);
						free(fstr); free(typestr);
						return false;
					}
				}
			
				/* length of slice/arr */
				t->kind = TYPE_BUILTIN;
				t->builtin = BUILTIN_I64;
				/* change expr to UNARY_LEN */
				e->kind = EXPR_UNARY_OP;
				Expression *of = lhs;
				e->unary.op = UNARY_LEN;
				e->unary.of = of;
			} else {
				char *s = type_to_str(lhs_type);
				err_print(e->where, "Operator . applied to type %s, which is not a structure or pointer to structure.", s);
				free(s);
				return false;
			}
		} break;
		} break;
	} break;
	case EXPR_TUPLE:
		t->kind = TYPE_TUPLE;
		t->tuple = NULL;
		arr_foreach(e->tuple, Expression, x) {
			Type *x_type = typer_arr_add(tr, &t->tuple);
			if (!types_expr(tr, x))
				return false;
			*x_type = x->type;
		}
		break;
	case EXPR_SLICE: {
		t->kind = TYPE_SLICE;
		SliceExpr *s = &e->slice;
		if (!types_expr(tr, s->of))
			return false;
		if (e->slice.from && !types_expr(tr, s->from))
			return false;
		if (e->slice.to && !types_expr(tr, s->to))
			return false;
		switch (s->of->type.kind) {
		case TYPE_ARR:
			t->slice = s->of->type.arr.of;
			break;
		case TYPE_SLICE:
			t->slice = s->of->type.slice;
			break;
		default: {
			char *str = type_to_str(&s->of->type);
			err_print(e->where, "Cannot take slice of non-array, non-slice type %s.", str);
			free(str);
			return false;
		}
		}
		break;
	}
	case EXPR_TYPE:
		if (!type_resolve(tr, &e->typeval, e->where))
			return false;
		t->kind = TYPE_TYPE;
		break;
	case EXPR_VAL:
		assert(0);
		return false;
	}
	t->flags |= TYPE_IS_RESOLVED;
	return true;
}

static bool typer_block_enter(Typer *tr, Block *b) {
	tr->block = b;
	*(Block **)arr_adda(&tr->blocks, tr->allocr) = b;
	if (!block_enter(b, b->stmts, SCOPE_CHECK_REDECL)) return false;
	return true;
}

static void typer_block_exit(Typer *tr) {
	Block *b = tr->block;
	block_exit(b, b->stmts);
	arr_remove_last(&tr->blocks);
	tr->block = *(Block **)arr_last(tr->blocks);
}

static bool types_block(Typer *tr, Block *b) {
	if (b->flags & BLOCK_FOUND_TYPES)
		return true;
	bool success = true;
	if (!typer_block_enter(tr, b))
		return false;
	b->ret_expr = NULL;
	arr_foreach(b->stmts, Statement, s) {
		if (!types_stmt(tr, s))
			success = false;
		else if (s->kind == STMT_EXPR && (s->flags & STMT_EXPR_NO_SEMICOLON)) {
			/* not voided */
			Expression *e = &s->expr;
			if (e->type.kind == TYPE_VOID) {
				if (!(e->kind == EXPR_BLOCK
					  || e->kind == EXPR_IF
					  || e->kind == EXPR_WHILE
					  || e->kind == EXPR_EACH)) {
					err_print(e->where, "void expression must be followed by ;");
					success = false;
					goto ret;
				}
			} else {
				if (s != (Statement *)arr_last(b->stmts)) {
					err_print(e->where, "Return value must be the last statement in a block.");
					success = false;
					goto ret;
				}
				b->ret_expr = typer_malloc(tr, sizeof *b->ret_expr);
				*b->ret_expr = *e;
				arr_remove_lasta(&b->stmts, tr->allocr);
			}
		}
	}
 ret:
	typer_block_exit(tr);
	b->flags |= BLOCK_FOUND_TYPES;
	return success;
}

static bool types_decl(Typer *tr, Declaration *d) {
	bool success = true;
	if (d->flags & DECL_FOUND_TYPE) return true;
	if (d->flags & DECL_INFER) {
		d->type.kind = TYPE_UNKNOWN;
		d->type.flags = 0;
		return true;
	}
	Declaration **dptr = typer_arr_add(tr, &tr->in_decls);
	*dptr = d;
	if (d->flags & DECL_ANNOTATES_TYPE) {
		/* type supplied */
		assert(d->type.kind != TYPE_VOID); /* there's no way to annotate void */
		if (!type_resolve(tr, &d->type, d->where)) {
			success = false;
			goto ret;
		}
	}
	if (d->flags & DECL_HAS_EXPR) {
		if (!types_expr(tr, &d->expr)) {
			success = false;
			goto ret;
		}
		if (d->flags & DECL_ANNOTATES_TYPE) {
			if (!type_must_eq(d->expr.where, &d->type, &d->expr.type)) {
				success = false;
				goto ret;
			}
			d->expr.type = d->type;
		} else {
			if (d->expr.type.kind == TYPE_VOID) {
				/* e.g. x := (fn(){})(); */
				err_print(d->expr.where, "Use of void value.");
				success = false;
				goto ret;
			}
			d->type = d->expr.type;
			d->type.flags &= (TypeFlags)~(TypeFlags)TYPE_IS_FLEXIBLE; /* x := 5; => x is not flexible */
		}
		if ((d->flags & DECL_IS_CONST) || (tr->block == NULL && tr->fn == NULL)) {
			if (!(d->flags & DECL_FOUND_VAL)) {
				Value val;
				if (!eval_expr(tr->evalr, &d->expr, &val)) {
					success = false;
					goto ret;
				}
				copy_val(tr->allocr, &d->val, &val, &d->type);
				d->flags |= DECL_FOUND_VAL;
			}
		}
				
	}
	for (size_t i = 0; i < arr_len(d->idents); ++i) {
		Type *t = d->type.kind == TYPE_TUPLE ? &d->type.tuple[i] : &d->type;
		if (t->kind == TYPE_TYPE) {
			if (!(d->flags & DECL_IS_CONST)) {
				err_print(d->where, "Cannot declare non-constant type.");
				success = false;
				goto ret;
			}
			if (d->flags & DECL_HAS_EXPR) {
				Value *val = d->type.kind == TYPE_TUPLE ? &d->val.tuple[i] : &d->val;
				if (!type_resolve(tr, val->type, d->where)) return false;
				if (val->type->kind == TYPE_TUPLE) {
					err_print(d->where, "You can't declare a new type to be a tuple.");
					success = false;
					goto ret;
				}
			}
		} else if (!(d->flags & DECL_IS_CONST) && t->kind == TYPE_FN && t->fn.constness) {
			for (size_t p = 0; p < arr_len(t->fn.types)-1; ++p) {
				if (t->fn.constness[p] == CONSTNESS_YES) {
					err_print(d->where, "You can't have a pointer to a function with constant parameters.");
					success = false;
					goto ret;
				}
			}
			/* make constness NULL, so that semi-constant parameters turn into non-constant arguments */
			t->fn.constness = NULL;
		}
	}

	{
		size_t n_idents = arr_len(d->idents);
		if (d->type.kind == TYPE_TUPLE) {
			if (n_idents != arr_len(d->type.tuple)) {
				err_print(d->where, "Expected to have %lu things declared in declaration, but got %lu.", (unsigned long)arr_len(d->type.tuple), (unsigned long)n_idents);
				success = false;
				goto ret;
			}
		}
	}
 ret:
	/* pretend we found the type even if we didn't to prevent too many errors */
	d->flags |= DECL_FOUND_TYPE;
	if (success) {
		if (d->flags & DECL_EXPORT) {
			/* export it! */
			if (!tr->exptr) {
				err_print(d->where, "Declaration marked for exporting, but no package output was specified."); 
				success = false;
			} else {
#ifdef TOC_DEBUG /* TODO: remove this */
				success = export_decl(tr->exptr, d);
#else
				err_print(d->where, "This feature is in progress.");
				success = false;
#endif
			}
		}
	} else {
		/* use unknown type if we didn't get the type */
		d->type.flags = TYPE_IS_RESOLVED;
		d->type.was_expr = NULL;
		d->type.kind = TYPE_UNKNOWN;
		tr->evalr->enabled = false; /* disable evaluator completely so that it doesn't accidentally try to access this declaration */
	}
	arr_remove_lasta(&tr->in_decls, tr->allocr);
	return success;
}

static bool types_stmt(Typer *tr, Statement *s) {
	switch (s->kind) {
	case STMT_EXPR:
		if (!types_expr(tr, &s->expr)) {
			return false;
		}
		if (s->expr.type.kind == TYPE_TUPLE && !(s->flags & STMT_EXPR_NO_SEMICOLON)) {
			err_print(s->where, "Statement of a tuple is not allowed. Use a semicolon instead of a comma here.");
			return false;
		}
		break;
	case STMT_DECL:
		if (!types_decl(tr, &s->decl))
			return false;
		break;
	case STMT_RET:
		if (!tr->fn) {
			err_print(s->where, "return outside of a function.");
			return false;
		}
		if (s->ret.flags & RET_HAS_EXPR) {
			if (tr->fn->ret_type.kind == TYPE_VOID) {
				err_print(s->where, "Return value in a void function.");
				return false;
			}
			if (tr->fn->ret_decls) {
				err_print(s->where, "Return expression in a function with named return values.");
				return false;
			}
			if (!types_expr(tr, &s->ret.expr))
				return false;
			if (!type_eq(&tr->fn->ret_type, &s->ret.expr.type)) {
				char *got = type_to_str(&s->ret.expr.type);
				char *expected = type_to_str(&tr->fn->ret_type);
				err_print(s->where, "Returning type %s in function which returns %s.", got, expected);
				return false;
			}
		} else {
			if (tr->fn->ret_type.kind != TYPE_VOID
				&& !tr->fn->ret_decls) {
				err_print(s->where, "No return value in non-void function.");
				return false;
			}
		}
		break;
	}
	return true;
}

static void typer_create(Typer *tr, Evaluator *ev, Allocator *allocr) {
	tr->block = NULL;
	tr->blocks = NULL;
	tr->fn = NULL;
	tr->evalr = ev;
	tr->exptr = NULL; /* by default, don't set an exporter */
	tr->in_decls = NULL;
	tr->in_expr_decls = NULL;
	tr->allocr = allocr;
	*(Block **)arr_adda(&tr->blocks, allocr) = NULL;
}

static bool types_file(Typer *tr, ParsedFile *f) {
	bool ret = true;
	arr_foreach(f->stmts, Statement, s) {
		if (!types_stmt(tr, s)) {
			ret = false;
		}
	}
	return ret;
}